Furnace with radiant tube therein



May 14, 1957 oNKowsKl 2,791,997

FURNACE WITH RADIANT TUBE THEREIN Filed Feb. 25,

HENRY l/. MONKOWS/(l,

his Attorney..

United States Patent F ACE WITH RADEANT TUBE "IHEREIN Henry V. Monkowski, Cleveland, Ohio, assignor to llnited States Steel Corporation, a corporation of New ersey Application February 23, 1955, vSerial No. 489,907

3 Claims. (Cl. 126-91) The present invention relates generally to gas fired radiant tubes and more particularly to a radiant tube having improved sectional construction especially suitable for use in metal heat treating furnaces.

Up to the time of my invention, certain types of gas fired radiant tubes utilized for heating conventional annealing furnaces were composed of a return bend section and two straight parallel pipe lengths all welded together to form a rigid unitary U-shaped structure. The rigid welded construction of such tubes increased their susceptibility to premature failure. Cracks frequently developed in one or more of the individual component sections due to the lack of flexibility in compensating for expansion and contraction brought about by heat changes during use. The cracks were usually brought about by undue strains set up at the welds between the pipe lengths and/or between the return bend and the pipe lengths. The cracks occurred before the tube burned out and necessitated replacement of the entire tube prematurely in order to maintain furnace efficiency.

It is, accordingly, an object of my invention to provide a sectional gas fired radiant tube for heating furnaces wherein the component sections of the tube are detachably and yieldably connected together and held together under compression whereby all the component sections of the tube are free to expand and contract in response to temperature changes.

This and other objects will become more apparent after referring to the following specification and attached drawings in which:

Figure 1 is a plan view; and

Figure 2 is an enlarged detail view partly in section.

Referring more particularly to the drawings, reference numeral 2 indicates generally a gas fired radiant tube constructed according to my invention and installed in a furnace heating chamber having a wall 5 on one side thereof. The tube 2 is made up of a return bend 4 having two substantially straight tubular limbs 6 and 8 extending therefrom to the wall 5 in substantially parallel relation. Limb 6 may consist `of three axially aligned individual pipe length sections 6a, 6b and 6c, and limb S may be made up of three axially aligned pipe lengths 8a and 8b and 8c.

A collar 10, which is provided with an inner circumferential flange 12 intermediate its ends, is loosely fitted around the junction of each pair of the adjacent pipe lengths with the flange 12 fitting between the adjacent ends of the pipe lengths. A collar is also loosely fitted around the junction of the pipe length 6a and the return bend 4 and the junction of the pipe length Sa and the return bend 4 with the flange 12 fitted between the ends of the return bend and the ends of the respective pipe lengths.

An elongated rod 14 is attached at one end to the return bend by means of a bracket 16 which is integral with the return bend. The rod 14 extends from its connection with the return bend in a horizontal plane substantially parallel to the limbs 6 and 8 with its free 2,791,997 Patented May 14, 1957 end projecting through and extending beyond the wall 5. A pair of adjusting nuts 18 are threaded on the projecting end of the rod 14 and serve as adjustable bearing or stop means for a helical spring 20 which is circumferentially lmounted on the projecting portion of the rod 14. The end of the spring 20 remote from the nuts 18 bears against the outer :surface of the wall 5. `The spring 20 serves to constantly zurge the rod 14 outwardly of the furnace chamber 3 and vthereby hold the various individual component sections of the .tube 2 yieldably together. `This arrangement permits the radiant tube to expand and contract freely lin response to temperature changes without the development of damaging cracks or other `defects which would lead to premature failure.

While I have .shown .each of the Acollars 10 as being provided with an inner circumferential flange 12 for the purpose of yieldably fixing the collars and pipe lengths in position, it will be noted that the inner circumferential flange 12 may be omitted and other means provided for fixing the collars 10 yieldably in position. For example, the individual pipe lengths may be shaped with necking down ends so that the collar 10 will be held in position by the larger diameter main body of the pipe lengths.

While one embodiment of my invention has been shown and described, it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. In a furnace having Walls defining a heating chamber, the improvement therewith of a radiant heating tube in said chamber for heating the same, said tube comprising a return bend disposed in said chamber and two limbs extending from said return bend in substantially parallel relation toward one of the walls of said furnace, the ends of said limbs remote from said return bend being supported by said one of said walls, means detachably connecting said limbs and said return bend together for limited axial movement of said limbs with respect to said return bend, each of said limbs being composed of a plurality of pipe lengths disposed end-toend, collar means detachably connecting said pipe lengths together for limited axial movement with respect to each other, an elongated rod attached at one end to said return bend and extending therefrom substantially parallel to said limbs with its other end projecting through and extending beyond said one of said walls, stop means on the projecting end of said rod, a spring circumferentially mounted on the projecting portion of said `rod with one end bearing against said stop means and its other end bearing against said one of said walls for urging said rod outwardly of said furnace to thereby hold said return bend and pipe lengths yieldably together.

2. In a furnace having walls defining a heating chamber, the improvement therewith of a radiant heating tube in said chamber for heating the same, said tube comprising a return bend disposed in said chamber and two limbs extending from said return bend in substantially parallel relation toward one of the walls of said furnace, the ends of said limbs remote from said return bend being supported by said one of said walls, a collar slidably fitted around the junction of each of said limbs and said return bend, each of said 'limbs being composed of a plurality of pipe lengths disposed end-to-end, a collar slidably fitted around each of the junctions of said pipe lengths, an elongated rod attached at one end to said return bend and extending therefrom substantially parallel to said limbs wilth its other end projecting through and extending beyond said one of said walls, stop means on the projecting end of said rod, a spring circumferentially mounted on the projecting portion of said rod with one end bearing against said stop means and its other end bearing against said one of said walls for urging said 3 rod outwardly of said furnace to thereby hold said return bend and pipe lengths yieldably together.

3. In a furnace having walls defining a heating chamber, the improvement therewith of a radiant heating tube in said chamber for heating the same, said tube comprising a return bend disposed in said chamber and two substantially straight limbs extending from said return bend in substantially parallel relation toward one of the walls of said furnace, the ends of said limbs remote from said return bend being supported by said one of said walls, a collar having an inner circumferential ange intermediate its ends slidably fitted around the junction of each of said limbs and said return bend with said ange fitting between the adjacent ends of said limbs and said return bend, each of said limbs being composed of a plurality of pipe Ilengths disposed end-to-end, a collar having an inner circumferential ange intermediate its ends slidably tted around each of the junctions of said pipe lengths with said ange fitting between the adjacent ends of said pipe lengths, an elongated rod attached at one end to said return bend and extending therefrom substantially parallel to said limbs with its other end projecting through and extending beyond said one of said walls, stop means on the projecting end of said rod, a spring circumferentially mounted on the projecting portion of said rod with one end bearing against said stop means and its other end bearing against said one of said walls for urging said rod outwardly of said furnace to thereby hold said return bend and pipe lengths yieldably together.

References Cited in the tile of this patent UNITED STATES PATENTS 

